U.S. patent number 6,504,463 [Application Number 09/521,794] was granted by the patent office on 2003-01-07 for coil and surface-mounting-type coil component.
This patent grant is currently assigned to Murata Manufacturing Co., Ltd.. Invention is credited to Hidekazu Kato, Tetsuya Morinaga.
United States Patent |
6,504,463 |
Kato , et al. |
January 7, 2003 |
Coil and surface-mounting-type coil component
Abstract
A surface-mounting-type coil component includes a wound coil, a
box-shaped core member, and a core member defining a cover. At two
ends of the coil, two extending portions are extended in opposite
directions so as to be separated by 180 degrees along a straight
line passing through the center of the wound coil. The box-shaped
core member includes a recess for accommodating the coil therein.
The four corners of the box-shaped core member have been removed.
Grooves are formed in a side wall defining the recess at 90 degree
intervals. Portions of the two extending portions are accommodated
in the grooves, with one end of each extending portion being
disposed at a mounting surface of the box-shaped core member so as
to be extended outwardly.
Inventors: |
Kato; Hidekazu (Takefu,
JP), Morinaga; Tetsuya (Fukui, JP) |
Assignee: |
Murata Manufacturing Co., Ltd.
(Kyoto, JP)
|
Family
ID: |
13298654 |
Appl.
No.: |
09/521,794 |
Filed: |
March 9, 2000 |
Foreign Application Priority Data
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Mar 12, 1999 [JP] |
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11-065841 |
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Current U.S.
Class: |
336/83; 336/192;
336/200; 336/232 |
Current CPC
Class: |
H01F
27/292 (20130101); H01F 27/027 (20130101); H01F
17/04 (20130101); H01F 2017/046 (20130101) |
Current International
Class: |
H01F
27/02 (20060101); H01F 27/29 (20060101); H01F
17/04 (20060101); H01F 027/02 () |
Field of
Search: |
;336/65,83,183,192,200,212,223,232 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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5-275253 |
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Oct 1993 |
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JP |
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6-310358 |
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Nov 1994 |
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JP |
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7-130560 |
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May 1995 |
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JP |
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7-245217 |
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Sep 1995 |
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JP |
|
7-288210 |
|
Oct 1995 |
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JP |
|
9-232154 |
|
Sep 1997 |
|
JP |
|
9-270334 |
|
Oct 1997 |
|
JP |
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10-41152 |
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Feb 1998 |
|
JP |
|
Primary Examiner: Donovan; Lincoln
Assistant Examiner: Nguyen; Tuyen T.
Attorney, Agent or Firm: Keating & Bennett, LLP
Claims
What is claimed is:
1. A coil comprising: an edgewise wound portion defined by a flat
wire having two major surfaces and edges extending between the two
major surfaces that is wound such that the major surfaces of the
flat wire extend in a horizontal direction and are stacked on each
other in a vertical direction and such that the edges of the flat
wire extend in the vertical direction and are substantially flush
with and stacked on each other in the vertical direction; and two
extending portions extending from upper and lower portions of the
edgewise wound portion, the two extending portions being arranged
to extend opposite to each other so as to be separated by an angle
of about 180 degrees along a line passing through a center of the
edgewise wound portion.
2. A coil according to claim 1, wherein an angle separating the two
locations of the edgewise wound portion from which the two
extending portions extend and an angle separating the two extending
portions are different.
3. A surface-mounting-type coil component, comprising: a coil
including an edgewise wound portion defined by a flat wire having
two major surfaces and edges extending between the two major
surfaces that is wound such that the major surfaces of the flat
wire extend in a horizontal direction and are stacked on each other
in a vertical direction and such that the edges of the flat wire
extend in the vertical direction and are substantially flush with
and stacked on each other in the vertical direction, and two
extending portions extending from upper and lower portions of the
edgewise wound portion, the two extending portions being arranged
to extend opposite to each other so as to be separated by an angle
of about 180 degrees along a line passing through a center of the
edgewise wound portion; and a core accommodating the coil
therein.
4. A surface-mounting-type coil component according to claim 3,
wherein the core comprises a first box-shaped core member having a
recess for accommodating the coil therein, and a second core member
arranged to cover an opening of the recess of the first box-shaped
core member.
5. A surface-mounting-type coil component according to claim 4,
wherein the recess is substantially rectangular.
6. A surface-mounting-type coil component according to claim 4,
wherein the recess is substantially circular.
7. A surface-mounting-type coil component according to claim 4,
wherein the first core member has a substantially box-shaped
configuration.
8. A surface-mounting-type coil component according to claim 4,
wherein the first box-shaped core member includes grooves for
accommodating the extending portions of the coil therein, the
grooves being formed in the first box-shaped core member so as to
be spaced from each other at approximately 90 degree intervals or
at approximately 180 degree intervals.
9. A surface-mounting-type coil component according to claim 4,
wherein a corner of the first box-shaped core member is
beveled.
10. A surface-mounting-type coil component according to claim 4,
wherein the first core member and the second core member are made
of a magnetic material.
11. A surface mounting-type coil component according to claim 4,
wherein the extending portions are bent along outer side walls of
the first core member, and the extending portions define
surface-mounting type external electrodes.
12. A surface-mounting-type coil component according to claim 3,
wherein at least one of the extending portions includes a first
portion that is bent upward at an angle of about 90 degrees and a
second portion that is bent at an angle of about 90 degrees
relative to the first portion.
13. A surface-mounting-type coil component according to claim 3,
wherein the first and second core members are arranged to define a
closed magnetic circuit.
14. A surface-mounting-type coil component according to claim 4,
the first box-shaped core member Includes four corners that are
beveled.
15. A surface-mounting-type coil component according to claim 3,
wherein the extending portions include portions which are disposed
at a mounting surface of the first core member and are bent to
define surface mounting external electrodes.
16. A surface-mounting-type coil component according to claim 3,
wherein the first core member is box-shaped and is arranged such
that substantially the entire box-shaped core member defines a
magnetic circuit.
17. A surface-mounting-type coil component according to claim 3,
wherein the core comprises a first core member having a recess for
accommodating the coil therein and a second core member arranged to
define a lid covering the coil and the first core member, the
recess of the first core member has a shape defined by opposing
curved lines each having a circumference that is about 1/4th that
of a circle and lines tangential to the curved lines.
18. A surface-mounting-type coil component according to claim 17,
wherein the first core member includes a substantially cylindrical
core portion located at an approximate center of the recess.
19. A surface-mounting-type coil component according to claim 3,
wherein the core has one of a substantially octagonal shape, a
substantially circular shape, and a substantially rectangular
shape.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coil and a surface-mounting-type
coil component, and more particularly, to a coil defined by flat
straight wire which has been edgewise wound and to a
surface-mounting-type coil component including the coil.
2. Description of the Related Art
Conventional surface-mounting-type coil components including
edgewise wound coils are shown in FIGS. 8 and 9. In the coil
component 1 illustrated in FIG. 8, a coil 2 is sandwiched between a
pair of E-shaped ferrite core members 3. The coil 2 is formed by
concentrically winding a straight wire into a circular
configuration (or by subjecting it to edgewise winding). Extending
portions 2a and 2b of the coil 2 extend parallel to each other and
in the same direction.
In the coil component 5 shown in FIG. 9, a coil 6 is accommodated
in a box-shaped ferrite core member 7. The coil 6 is defined by a
flat straight wire which has been edgewise wound. A ferrite core
member 8 is inserted into a hole 6c in the center portion of the
coil 6, and a ferrite core member 9 defining a cover is placed on
the core member 8 and the coil 6 to cover them. Extending portions
6a and 6b of the coil 6 are extended parallel to each other and in
the same direction.
Ordinarily, the extending portions 2a and 2b of the coil 2 of the
coil component 1 are bent along the surfaces of the ferrite core
members 3 in order to be used as surface-mounting external
electrodes. Similarly, the extending portions 6a and 6b of the coil
6 of the coil component 5 are bent along the surface of the ferrite
core member 7 in order to be used as surface-mounting external
electrodes. However, the extending portions 2a and 2b of the
conventional coil component 1 and the extending portions 6a and 6b
of the conventional coil component 5 are arranged at one side of
the center of the windings of the coil 2 and at one side of the
center of the windings of the coil 6, respectively. Therefore, the
coils 2 and 6 in the axial direction are such that the side where
the extending portions 2a and 2b and the side where the extending
portions 6a and 6b are located are higher than the opposite side
where the extending portions 2a and 2b are not located and the
opposite side where the extending portions 6a and 6b are not
located, respectively. Consequently, when, for example, as shown in
FIG. 10, the extending portions 2a and 2b of the coil 2 are bent
along the surfaces of the ferrite core members 3, the coil 2
becomes tilted, often causing end portions of the extending
portions 2a and 2b to be elevated relative to the surfaces of the
ferrite core members 3. This prevents the mounting surface of the
conventional coil component 1 from being level, thereby making the
component 1 difficult to mount on a printed circuit board.
In addition, when the coil components 1 and 5 are to be mounted on
a printed circuit board or other substrate, the surface-mounting
external electrodes defined by bending the extending portions 2a
and 2b and the surface-mounting external electrodes defined by
bending the extending portions 6a and 6b are disposed only on one
side of the coil component 1 and the coil component 5,
respectively. Thus, the coil components 1 and 5 may get pulled to
one side and may be mounted in a tilted state. Further, after being
mounted on a printed circuit board, the coil components 1 and 5 are
unstable.
The box-shaped ferrite core member 7, the ferrite core member 8,
and the ferrite core member 9 of the coil component 5 define a
magnetic circuit that is superior to that defined by the pair of
E-shaped ferrite core members 3 of the coil component 1. However,
even with the magnetic circuit of the coil component 5, the
extending portions 6a and 6b of the coil 6 disposed at one side of
the center of the windings of the coil 5 locally interrupt the
magnetic path, so that magnetic flux lines tend to concentrate at
the side where the extending portions 6a and 6b are not disposed
(at side A in FIG. 9), which is opposite to the side of the
extending portions 6a and 6b. Therefore, magnetic saturation easily
occurs, thereby it is difficult to generate inductance with high
efficiency. Further, portions P1 at the four corners of the core
member 3 of the coil component 1 and portions P2 at the four
corners of the core member 7 of the coil component 5 do not
function effectively as magnetic circuits, as a result of which
space is wasted.
SUMMARY OF THE INVENTION
To overcome the problems described above, preferred embodiments of
the of the present invention provide a coil and a
surface-mounting-type coil component, which enhances mountability
and which achieves highly efficient inductance.
According to a preferred embodiment of the present invention, a
coil includes an edgewise wound portion and two extending portions
extending from two locations of the edgewise wound portion, the two
extending portions being arranged to extend opposite to each other
so as to be separated by an angle of 180 degrees along a straight
line passing through a center of the edgewise wound portion.
This unique structure and arrangement makes it possible to extend
the extending portions of the coil using the technique used to wind
a straight wire in an edgewise manner. In other words, the
extending portions from the respective end of edgewise winding can
be easily extended by edgewise bending.
An angle defined by the two locations where the edgewise winding is
terminated and an angle formed by the two extending portions may
differ. Since the directions in which the extending portions are
extended are not restricted, any coil inductance value can be
set.
According to another preferred embodiment of the present invention,
a surface-mounting-type coil component includes a coil having an
edgewise wound portion and two extending portions extending from
two locations of the edgewise wound portion, the two extending
portions being arranged to extend opposite to each other so as to
be separated by an angle of 180 degrees along a straight line
passing through a center of the edgewise wound portion, and a core
accommodating the coil therein.
The core may preferably be a first core member having a recess for
accommodating the coil therein, and a second core member defining a
cover and arranged to cover the recess of the first core
member.
The first core member is preferably box shaped and may include
grooves for accommodating the extending portions of the coil
therein. The grooves are preferably located in a side wall defining
the recess at 90 degree intervals or at 180 degree intervals.
By virtue of the above-described structures, the two extending
portions of the coil are extended in opposite directions so as to
be separated by 180 degrees along the straight line that passes
through the center of the edgewise wound portion of the coil.
Therefore, even when the extending portions are bent along the
surface of the core, they are not elevated from the surface of the
core. In addition, the surface-mounting external electrodes defined
by bending the extending portions are disposed on both sides of the
coil component. Therefore, the coil component will not be mounted
in a tilted state on a printed circuit board or other substrate,
thereby eliminating shaking of the coil component that has been
mounted on the printed circuit board. Further, since the extending
portions of the coil are not disposed at one side of the center of
the winding of the coil, magnetic flux lines are not concentrated
at local portions of the core, thereby improving magnetic
saturation properties.
When the core includes a box-shaped core member and another core
member which defines a cover, a corner of the box-shaped core
member may be removed. This allows substantially the entire
box-shaped core member to function effectively as a magnetic
circuit.
When the box-shaped core member includes grooves for accommodating
the extending portions of the coil therein, a corner of the
box-shaped core member may be removed.
Other features, elements, advantages and charactestics of the
present invention will become apparent from the following detailed
description of preferred embodiments with reference to the attached
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of a first preferred
embodiment of the coil and the surface-mounting-type coil component
in accordance with the present invention.
FIG. 2 is an external perspective view of the surface-mounting-type
coil component shown in FIG. 1, as seen from the mounting surface
side.
FIG. 3 is an exploded perspective view of a second preferred
embodiment of the coil and the surface-mounting-type coil component
in accordance with the present invention.
FIG. 4 is a vertical sectional view of the surface-mounting-type
coil component shown in FIG. 3.
FIG. 5 is a bottom view of the surface mounting type coil component
shown in FIG. 3.
FIG. 6 is a bottom view of a modification of the
surface-mounting-type coil component shown in FIG. 3.
FIG. 7 is an exploded perspective view of a third preferred
embodiment of the coil and the surface-mounting-type coil component
in accordance with the present invention.
FIG. 8 is an exploded perspective view of a conventional coil
component.
FIG. 9 is an exploded perspective view of another conventional coil
component.
FIG. 10 is a side view of the coil component shown in FIG. 8.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
A description will now be provided of preferred embodiments of the
coil and the surface-mounting-type coil component in accordance
with the present invention, with reference to the drawings.
A description will now be provided of a first preferred embodiment
of the surface-mounting-type coil component, with reference to
FIGS. 1 and 2. As shown in FIG. 1, a surface-mounting-type coil
component 11 preferably includes a coil 12, a first core member 13
preferably having a substantially rectangular box shape, and a
second core member 14 defining a lid arranged to cover the coil 12
and the first core member 13. The coil 12 is preferably formed by
concentrically winding a flat straight wire into a substantially
circular configuration or by subjecting the flat straight wire to
edgewise winding). The straight wire is, for example, a straight
copper wire (a ribbon or a metal foil) with an insulating film,
such as a polyurethane film or a polyester film, provided on its
surface.
In the coil 12, an extending portion 12b is extended outwardly by
edgewise bending from a winding terminated location 25 located at
the upper side of the coil 12 in an axial direction thereof.
Similarly, an extending portion 12a is extended outwardly by
edgewise bending from a winding-termination location located at the
lower side of the coil 12 in the axial direction thereof. When the
extending portion 12a is extended outwardly, a portion thereof is
bent upward at an angle of about 90 degrees, and then bent again at
an angle of about 90 degrees so that it lies in the same plane as
the plane in which the extending portion 12b lies. In other words,
the extending portions 12a and 12b are extended in opposite
directions so that they are separated by about 180 degrees along a
straight line L that passes through the center of the edgewise
wound portion 12c. Accordingly, the extending portions 12a and 12b
can easily be extended outwardly from the edgewise wound portion
12c by carrying out edgewise bending, that is, an edgewise winding
technique.
A substantially rectangular recess 21 is provided in the
approximate center portion of a mounting surface 13b of the
substantially rectangular box-shaped core member 13 in order to
accommodate the coil 12 therein. A substantially cylindrical core
portion 22 is provided in the approximate center portion of the
recess 21. The lid core member 14 to cover is used to cover the
recess 21 in the box-shaped core member 13. The core members 13 and
14 are preferably made of, for example, an insulating material or a
magnetic material. In the first preferred embodiment, a magnetic
material, such as a ferrite material, is preferably used to form
the box-shaped core member 13 and the lid core member 14.
Therefore, the core members 13 and 14 which are combined define a
closed magnetic circuit.
The insulating films on the surfaces of the extending portions 12a
and 12b of the coil 12 are removed in advance, after which, if
necessary, the extending portions 12a and 12b may be subjected to
solder plating operations and solder dipping operations. Removal of
the insulating films from the extending portions 12a and 12b or
solder plating operations on the extending portions 12a and 12b do
not necessarily have to be previously carried out early in the
forming process of the coil component 11. Such processes may be
carried out later in the forming process of the coil component 11.
The coil 12 is then accommodated in the recess 21 in the box-shaped
core member 13, and the core portion 22 is inserted into a hole 12c
defined in the approximate center portion of the coil 12. After the
insertion of the core portion 22, the extending portions 12a and
12b of the coil 12 are disposed at the mounting surface 13b of the
box-shaped core member 13 in order to be extended outwardly. After
the extending portions 12a and 12b have been extended outwardly,
the lid core member 14 to cover is placed on the coil 12 in order
to cover an opening of the recess 21. Thereafter, if necessary, the
recess 21 may be filled with resin (or an adhesive) 18.
As shown in FIG. 2, the extending portions 12a and 12b of the coil
12 disposed at the mounting surface 13b of the box-shaped core
member 13 are bent along respective outer side walls 13a of the
box-shaped core member 13 in order to be used as surface-mounting
external electrodes.
In the surface-mounting-type coil component 11 having the
above-described structure, the extending portions 12a and 12b of
the coil 12 are extended opposite to each other so that they are
separated by about 180 degrees along the straight line L that
passes through the center of the edgewise wound portion 12c.
Therefore, even when the extending portions 12a and 12b are bent
along their respective side walls 13a of the box-shaped core member
13, they are not elevated from the mounting surface 13b. As a
result, the mounting surface 13b of the coil component 11 is
reliably located at a correct level position, thereby greatly
improving the mountability of the component on a printed circuit
board or other substrate.
In addition, in the surface-mounting-type coil component 11, since
the surface mounting external electrodes defined by the bent
extending portions 12a and 12b are arranged opposite each other,
the coil component 11 is mounted reliably and stably at a a level
position on a printed circuit board or substrate. Therefore, the
coil component 11 is reliably and securely mounted and does not
experience shaking or instability after it has been mounted on the
printed circuit board or substrate.
Further, in the surface-mounting-type coil component 11, since the
extending portions 12a and 12b of the coil 12 are disposed
symmetrically opposite each other with respect to the center of the
windings of the coil 12 so as to be separated by about 180 degrees,
the magnetic flux lines in the magnetic path defined by the core
members 13 and 14 will not flow to one side. The magnetic flux is
not biased or slanted. This greatly improves magnetic saturation
properties, so that the coil component 11 generates the inductance
with high efficiency.
A description will now be provided for a second preferred
embodiment of the surface-mounting-type coil component with
reference to FIGS. 3 to 6. As shown in FIG. 3, the
surface-mounting-type coil component 31 preferably includes a coil
32, a first core member 33 having a substantially rectangular
box-shape, and a second core member 34 arranged to cover the
component 31 and the first core member 33. The coil 32 is
preferably formed by concentrically winding a flat straight wire
into a substantially circular form or by forming it into an
edgewise winding.
In the coil 32, an extending portion 32b is extended outwardly by
edgewise bending from a winding-termination location 45 disposed at
the upper side of the coil 32 in an axial direction thereof. When
the extending portion 32b is extended outwardly, a portion thereof
is bent upward at an angle of about 90 degrees, and then a
predetermined portion thereof is bent again at an angle of about 90
degrees towards the outer side. Similarly, an extending portion 32a
is extended outwardly by edgewise bending from a
winding-termination location disposed at the lower side of the coil
32 in the axial direction thereof. When the extending portion 32a
is extended outwardly, a portion thereof is bent upward at an angle
of 90 degrees, and then a predetermined portion thereof is bent
again at an angle of 90 degrees towards the outer side so as to lie
in the same plane in which the plane of the extending portion 32b
lies. The extending portions 32a and 32b are extended outwardly in
opposite directions so that they are separated by about 180 degrees
along a straight line L that passes through the center of the
edgewise wound portion. Accordingly, the extending portions 32a and
32b can be easily extended outwardly by edgewise bending, that is,
an edgewise winding technique.
A substantially circular recess 41 is located at the approximate
center portion of a mounting surface 33b of the box-shaped core
member 33 in order to accommodate the coil 32 therein. The four
corners of the box-shaped core member 33 are removed and beveled. A
substantially cylindrical core portion 42 is provided in the
approximate center of the recess 41. This core portion 42 does not
have to be integral with the box-shaped core member 33. Grooves 43
are located in the side wall defining the recess 41 at
approximately 90 degree intervals. In other words, the grooves 43
are arranged so as to oppose respective cut-away portions (or
beveled corners) 33a defined by removing the four corners of the
box-shaped core member 33. There are four of these grooves 43
provided at approximate 90 degree intervals in order to eliminate
directional limitations during assembly of the coil component 31.
It is possible to assemble the coil component 31 in either
direction.
The lid core member 34 is arranged to cover the recess 41 in the
box-shaped core member 33. The core member 33 and the lid core
member 34 are preferably made of, for example, an insulating
material or a magnetic material. In the second preferred
embodiment, ferrite or other magnetic materials are used to form
the core members 33 and 34. The core members 33 and 34 together
define a closed magnetic circuit.
The coil 32 is accommodated in the recess 41 provided in the core
member 33, and the core portion 42 is inserted into a hole 32c
provided in the approximate center of the coil 32. Then, a portion
of the extending portion 32a and a portion of the extending portion
32b are accommodated in any two opposing grooves 43. One end
portion of the extending portion 32a and one end portion of the
extending portion 32b are disposed at the mounting surface 33b of
the core member 33 so as to extend outwardly. Thereafter, the core
member 34 is placed on the coil 32 in order to cover an opening of
the recess 41, after which, if necessary, the recess 41 may be
filled with resin or adhesive 38 (see FIG. 4).
As shown in FIGS. 4 and 5, the extending portions 32a and 32b
disposed at the mounting surface 33b of the core member 33 are bent
along their corresponding cut-away portions (beveled corners) 33a
of the core member 33 in order to be used as surface mounting
external electrodes.
In the surface-mounting-type coil component 31 having the
above-described structure, the extending portions 32a and 32b of
the coil 31 are extended opposite each other so that they are
separated by about 180 degrees along the straight line L that
passes through the center of the edgewise wound portion. Therefore,
even when the extending portions 32a and 32b are bent along
respective cut-away portions 33a of the box-shaped core member 33,
they are not elevated from the mounting surface 33b. As a result,
the mounting surface 33b of the coil component 31 is reliably
located in its proper level position, thereby greatly improving
mountability with respect to, for example, a printed circuit board
or substrate.
In addition, in the surface-mounting-type coil component 31, since
the surface-mounting external electrodes defined by bending the
extending portions 32a and 32b, are provided opposite each other,
the coil component 31 is located at its proper level position when
it is mounted on, for example, a printed circuit board. Therefore,
it does not cause the problem of the coil component 31 being
unstable and shaking after it has been mounted on the printed
circuit board.
Further, in the surface-mounting-type coil component 31, since the
extending portions 32a and 32b of the coil 32 are disposed
symmetrically opposite each other with respect to the center of the
windings of the coil 32 so as to be separated by about 180 degrees,
the magnetic flux lines in the magnetic path defined by the core
members 33 and 34 will not flow to one side. This improves magnetic
saturation properties, so that a coil component 31 generates the
inductance with high efficiency.
Still further, by removing the corners of the core member 33,
substantially the entire box-shaped core member 33 functions
effectively as a magnetic circuit, so that space is not wasted.
This allows inductance to occur even more efficiently. The cutouts
43 may be formed at approximately 180 degree intervals in the side
wall defining the recess 41, as shown in FIG. 6.
A description will now be provided of a third preferred embodiment
of the surface-mounting-type coil component, with reference to FIG.
7. A surface-mounting-type coil component 51 of the third preferred
embodiment includes a coil in which the angle defined by the two
winding-termination locations and that defined by the two extending
portions are different. As shown in FIG. 7, the
surface-mounting-type coil component 51 includes a coil 52, a first
core member 53 having a substantially rectangular box-shape, and a
second core member 54 defining a lid and arranged to cover the coil
52 and the first core member 53. The coil 52 is preferably formed
by subjecting a straight wire to edgewise winding. The core members
53 and 54 are made of, for example, an insulating material or a
magnetic material.
In the coil 52, an extending portion 52b is extended outwardly by
edgewise bending from a winding-termination location 65 located at
the upper side of the coil 52 in an axial direction thereof.
Similarly, an extending portion 52a is extended outwardly by
edgewise bending from a winding termination location located at the
lower side of the coil 52 in the axial direction thereof. When the
extending portion 52a is extended outwardly, a portion thereof is
bent upward at an angle of about 90 degrees, and then bent inwardly
at an angle of about 90 degrees in the same plane as the plane in
which the extending portion 52b lies. Then, the extending portion
52a is subjected to edgewise bending so as to extend outwardly. The
two winding-termination locations 65 of the coil 52 defines an
angle of about 90 degrees relative to each other, while the two
extending portions 52a and 52b defines an angle of about 180
degrees relative to each other.
A recess 61 is provided in the approximate center portion of a
mounting surface 53b of the substantially rectangular, box-shaped
core member 53 in order to accommodate the coil 52 therein. The
recess 61 preferably has a shape defined by opposing curved lines,
each with a circumference that is about 1/4th that of a circle, and
lines tangential to the curved lines. The lid core member 54 can be
easily disposed in the proper position in the recess 61 with this
shape, thereby reducing variations in the inductance values. A
substantially cylindrical core portion 62 is provided in the
approximate center of the recess 61.
The coil 52 is accommodated in the recess 61 provided in the
box-shaped core member 53, and the substantially cylindrical core
portion 62 is inserted into a hole 52c provided in the approximate
center portion of the coil 52. Then, the extending portions 52a and
52b of the coil 52 are disposed at the mounting surface 53b of the
box-shaped core member 53. Thereafter, the core member 54 to cover
is placed on the coil 52 in order to cover the recess 61, and, if
necessary, the recess 61 may be filled with resin or adhesive 38
(see FIG. 4).
The extending portions 52a and 52b of the coil 52 disposed at the
mounting surface 53b of the box-shaped core member 53 are bent
along respective side walls 53a of the core member 53 in order to
be used as surface-mounting external electrodes.
The surface-mounting-type coil component 51 having the
above-described structure provides the same operational advantages
as the surface-mounting-type coil component 11 of the first
preferred embodiment. In the coil component 11 of the first
preferred embodiment, the angle defined by the two winding
termination locations 25 of the coil 12 and that defined by the
extending portions 12a and 12b are the same, (in other words, the
directions in which the winding-termination locations 25 and the
extending portions 12a and 12b are extended are the same). In
contrast, in the coil component 51 of the third preferred
embodiment, the extending portions 52a and 52b are extended so that
the directions in which the two winding-termination locations 65 of
the coil 52 are oriented are set independently of the directions in
which the extending portions 52a and 52b extend. The angle defined
by the positions of the two winding-termination 65 are set
differently from the angle defined by the extending direction of
the extending portions 52a and 52b. As a result, the angle defined
by the two winding-termination locations 65, (i.e. positions of the
two winding-termination), may be set arbitrarily at any value,
making it possible to set the inductance of the coil 52 at a
desired value.
It is to be noted that the present invention is not limited to the
above-described preferred embodiments of the surface-mounting-type
coil component, so that various modifications may be made within
the gist and scope of the invention. For example, the form of the
box-shaped core member may be modified. Although the box-shaped
core member shown in FIG. 3 has a substantially octagonal in shape
as a result of removing the four corners thereof, and the
box-shaped core member shown in FIG. 6 is substantially hexagonal
in shape as a result of removing two corners thereof, it can be
formed into any other polygonal shape, or into a substantially
circular or a substantially rectangular shape in accordance with
the specification of the product demanded by the user. In addition,
the coil accommodating portion may be structured differently.
Although in the above-described preferred embodiments the coil
accommodating portion is defined by a combination of a box-shaped
member and a lid core member, it may be formed by combining two
box-shaped core members arranged to engage with each other or to
abut against each other, in the interior of which the coil is
accommodated.
As can be understood from the foregoing description, according to
the present invention, two extending portions of a coil are
extended in opposite directions so as to be separated by about 180
degrees along a straight line passing through a center of the
edgewise wound portion of the coil. Therefore, even when the
extending portions are bent along the surface of the core member,
they are not elevated therefrom. This allows a mounting surface of
the coil component to be reliably mounted stably and securely
level, thereby greatly improving mountability of the coil component
with respect to, for example, a printed circuit board or substrate.
In addition, the extending portions of the coil can be extended by
the technique used to wind a straight wire edgewise. In other
words, from their respective winding-termination locations, the
extending portions can be easily extended opposite to each other so
as to be separated by about 180 degrees by edgewise bending.
In addition, according to the present invention, since the
surface-mounting external electrodes defined by bending the
extending portions are disposed at both sides of the coil
component, the coil component is reliably positioned at its proper
level position when it is mounted on, for example, a printed
circuit board or substrate. As a result, shaking of the coil
component after it has been mounted to the printed circuit board is
eliminated. In the present invention, the extending portions of the
coil are not provided only at one side of the center of the
windings of the coil, and the compnent is not disposed in an
inclined position, so that local concentration of magnetic flux
lines does not occur at the core member. This improves magnetic
saturation properties of the core member, making it possible to
provide a coil component that allows inductance to occur with high
efficiency.
Further, according to the present invention, by cutting the corners
of the box-shaped core member, substantially the entire box-shaped
core member can function effectively as a magnetic circuit.
Therefore, inductance is generated with even greater efficiency, as
a result of which space is not wasted.
While preferred embodiments of the invention have been disclosed,
various modes of carrying out the principles disclosed herein are
contemplated as being within the scope of the following claims.
Therefore, it is understood that the scope of the invention is not
to be limited except as otherwise set forth in the claims.
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